The present invention relates to a vehicle for a rail-borne transportation system and to a rail-borne transportation system, particularly in the form of a magnetic levitation railway, which is operated using the a vehicle.
Particularly in the case of a magnetic levitation railway, vehicles of this type are driven, e.g., by elongated stator-linear motors, and, in order to drive the vehicles, they include certain three-phase alternating current windings placed in an elongated stator along the track system. The excitation field of the linear motors is delivered by supporting magnets which simultaneously function as excitation magnets and are located in the vehicle, and which form a first magnet system (e.g., DE 39 17 058 C2). The linear motors may be used for driving and for braking the vehicles.
In addition, the vehicles of the type described initially each include a second magnet system, preferably on both sides, which is used for “guidance”, and which includes a plurality of magnetic poles located one after the other in the direction of travel, and windings assigned thereto (e.g., DE 10 2004 056 438 A1). They are operated using current in such a manner that all of the magnetic poles situated in a row or plane parallel to the direction of travel have the same polarity or orientation. In addition, these magnet systems are controlled using closed-control loops and assigned gap sensors such that a gap, which is referred to as a guide gap, between the magnetic poles, and ferromagnetic lateral guide rails installed on either side of the track system are always maintained at the same values.
Since braking cannot be carried out, e.g., if any or all of the support and excitation magnets or the drive system fail, magnetic levitation trains designed for use at high speeds are also equipped with a “safety” brake which is preferably composed of an eddy current brake (DE 10 2004 013 994 A1). An eddy current brake of this type is formed by a third magnet system which is located between the magnet systems to perform a “guidance” function. This third magnet system interacts with an electrically conductive reaction rail, preferably with the lateral guide rail, and includes a plurality of magnetic poles situated one after the other in the direction of travel, which, in contrast to the magnetic poles in the guide magnet system, are operated using different polarities, preferably using north and south poles in an alternating manner. As a result, when braking is activated, eddy currents are produced in the reaction rail; the eddy currents brake the magnetic levitation vehicle heavily or gently depending on the speed of the magnetic leviation vehicle and the magnitude of the direct current which is directed through the windings of the brake magnet system.
Due to the design, described above, of typical eddy current brakes, their electromagnetic poles must be activated for braking by switching on relatively high electrical currents (e.g., 80 A direct current). It is therefore necessary to equip the magnetic levitation vehicles with electrical energy accumulators having large storage capacities, which are designed as batteries and are used only in an emergency situation. This is uneconomical, results in a considerable increase in the total weight and amount of space required, and is undesired since it requires continual maintenance.
Eddy current brakes of this type may also be provided for other rail-borne transportation systems. In the case of a wheel/rail system, the vehicles could be equipped, e.g., with eddy current brakes that interact with conventional rails which would therefore function simultaneously as driving rails and reaction rails in this case.